Substance P is released from which type of neuron?

Substance P is released from which type of neuron?

• A. Interneurons
• B. Primary afferent (nociceptive) neurons
• C. Glial cells
• D. Motor neurons

Answer: (B)

Pain signaling hinges on Substance P being released from primary afferent nociceptors. These are small-diameter sensory neurons with cell bodies in the dorsal root ganglia that detect tissue damage. When they are activated by noxious stimuli, their central terminals in the spinal cord release Substance P (often with glutamate) to enhance the activity of second-order neurons and to promote inflammation via NK1 receptors. This release is characteristic of the nociceptive pathway, making it the best answer. Interneurons can modulate pain but are not the main source of Substance P for transmitting the initial nociceptive signal; glial cells and motor neurons have other roles and do not serve as the primary source of Substance P release in this context.

Pain signaling hinges on Substance P being released from primary afferent nociceptors. These are small-diameter sensory neurons with cell bodies in the dorsal root ganglia that detect tissue damage. When they are activated by noxious stimuli, their central terminals in the spinal cord release Substance P (often with glutamate) to enhance the activity of second-order neurons and to promote inflammation via NK1 receptors. This release is characteristic of the nociceptive pathway, making it the best answer. Interneurons can modulate pain but are not the main source of Substance P for transmitting the initial nociceptive signal; glial cells and motor neurons have other roles and do not serve as the primary source of Substance P release in this context.